Pneumatically controlled servo valve



United States Patent [72] Inventor Emanuel Briguglio Wheaton, Maryland[21] AppLNo. 743,239 [22] Filed July8,1968 [45] Patented Dec. 1,1970[73] Assignee Singer-General Precision, Inc.

Binghamton, New York a corporation of Delaware [54] PNEUMATICALLYCONTROLLED SERVO VALVE 3 Claims, 1 Drawing Fig.

[52] U.S.Cl ..l37/625.62, 137/81.5 [51] Int.Cl Fl5c3/02, F16k3l/12 [50]FieldofSearch 137/815, 82, 83, 625.62, 625.63

[56] References Cited UNITED STATES PATENTS 3,233,623 2/1966 Glayl37/625.62X 3,407,828 10/1968 Jones 137/815 3,444,877 5/1969 Atchley137/815 H 13,s43,79s

FOREIGN PATENTS 1,458,767 10/1966 France ABSTRACT: A control blockcontains an input, two outputsand two control input ports. Fluidpressure is continuously applied to the system input, and fluid pressureis continuously exhausted from the two outputs in equal amounts. The twooutput ports expel the exhausted fluid against opposite sides of a vane.Normally, the vane is thereby maintained in a central position. When afluid pulse is applied to one of the control inputs or the other, thefluid is deflected in the control block so that more is delivered to oneoutput port than to the other. The vane is thereby deflected toone side,The vane is pivoted on a fixed mount at one end and is pivoted on aslideable spool I at the other end. When the vane is deflected to oneside or the other, the spool is also moved from a central position. Thespool contains a plurality of pistons which fit in a cylinder in a valvehousing, and'when the spool is moved to one side or another, a source offluid under pressure is connected through an input port to one or theother of a pair of output ports. The direction of movement determineswhich of the two output ports receives the fluid.

XXXXX' XXXXX Patented Dec. 1, 1970 3,543,798

INVENTOR. EMANUEL BRIGUGLIO PNEUMATICALLY CONTROLLED SERVO VALVE Thisinvention relates to control devices and, more particularly, to fluidcontrol systems in which a large fluid pressure or quantity can besimply and accurately controlled by a small, pulsed or proportionalanalog source of fluid pressure.

Fluid servo systems are becoming more common. In fact, in a largeproportion of today's automobiles, the braking system contains a fluidservo assist device. Fluid servo systems have been used for many yearsas door operators and in many manufacturing and other mechanicalsystems. However, most of the prior art fluid servo systems have been ofthe amplifier type where the output is but an amplification of arelatively steady state input. The input was one which varied slightlyin pressure in response to such things as the amount of move ment of amember to produce an amplified movement or a proportional movement of alarger device or both.

Recently, as the utilization and the requirements of digital computershas expanded, development of digital systems using energy sources otherthan electricity has also taken place. One of these energy sources is asource of fluid pressure. The field of fluidics has developed as adigital or pulsed fluid system where a source of fluid pressure iscontrolled by fluid pulses. In most applications of the pulsed fluidsystems, amplification is not required other than to overcome losseswithin the system. However, the applications of pulsed fluid controlsystems could be increased if the systems would amplify as well ascontrol.

it is an object of this invention to provide a new and improved pulsedfluid control system.

lt is another object of this invention to provide a new and improvedpulsed fluid control system in which both the input signals and theoutput fluid signals are pulsed.

It is a further object of this invention to provide a new and improvedpulsed fluid control system in which relatively weak fluid pulsescontrol a considerably larger fluid output system.

Other objects and advantages of this invention will become apparent asthe following description proceeds, which description should beconsidered together with the accompanying drawings in which the singleFIG. is a schematic showing in section of the fluid control system ofthis invention.

Referring now to the drawing in detail, the reference character 11designates a valve housing having a central cavity with partitionsmounted therein. The housing 11 includes a fluid supply port 12,.a rightfluid output port 13, a left fluid output port 14 and a fluid exhaustport 15. The ports 12l5 are connected with the central cavity of thehousing 11 by means of a filter 16 and a spool valve which includes aspool 20 having right pistons 24 and 25 and left pistons 22 and 23. Thecentral cavity includes passageways 27 and 28. Passageway 27 terminatesexternally at one end in a diaphragm having a central opening 31therethrough and internally at the other end in a small opening 51 whichconnects with the supply port 12. Similarly, passageway 28 terminatesexternally at one end in a diaphragm having a central perforation 32,and internally at its other end in a small opening 51 which connectswith the supply port 12. The two perforations 31 and 32 face oppositesides of a vane which is pivotally attached to the spool 20 at one endand is mounted on an anchored pivot 41 at the other end. The system alsoincludes'a control block 50 having a fluid supply input 42. Within theblock '50, the inputpassage 42ends in a fork which dividesthe singleinput 42 into two identical passages 45 and 46. The passage 45 ends in atube 48 which terminates adjacent the same side of the vane 30 astheperforation 3'1, and .the passage 46 ends in a tube 49 whichterminates adjacent the other side of the vane 30 as does .theperforation '32. In addition, two signal input ports 43 and 44 terminatewithin the block 50 at the fork 47.

The system of this invention -will operate as a fluid servo system ifthe information supplied to the'two signal input ports 43 and 44 is inthe-form of-pulses of fluidpressure'applied to one or both-of the inputs43 and 44, is in the form "of a slowly varying steady-state orcontinuous fluid pressure applied, say, differentially to the two inputs43 and 44, or is-in-the form ofa frequency-or amplitude modulatedcontinuous fluid pressure applied to one or both of the inputs 43 and44. For the purposes of this description, it is assumed that informationis applied to one of the inputs 43 and 44 at a time in the form of fluidpulses.

In operation with fluid under pressure supplied to the input port 12 andto the fluid input supply 42, fluid passes through the two passages 45and 46 in the control block 50 and impinges equally on the two sides ofthe vane 30 from the ends of the tubes 48 and 49. Also, fluid underpressure bleeds through the two small openings 51 from the input port12, passes through the passageways 27 and 2 8 in the housing 11, and isexpelledequally from the two perforations 31 and 32 against oppositesides of the vane 30. Thus, with fluid from both the control block 50and the housing 11 impinging equally on the opposite sides of the vane30, the vane 30 tends to stay in a central position and tends tomaintain the spool 20 in a central position. In the central position,the fluid entering the input port 12 is blocked from both of the outputports 13 and 14 by the pistons 25 and 22, and the exhaust port 15 isopen to the atmosphere at both ends. In this condition, the system isbalanced.

The application ofa fluid pulse to either of the signal inputs 43 or 44unbalances the system and causes an action. Assume that a pulse of fluidis applied to the input 43. The stream of fluid flowing from the supplyinput 42 to the two outputs 45 and 46 is deflected by the input pulse sothat more fluid is forced through the output 46 than through 45. Morefluid under pressure is expelled from the output tube 49 than from 48,and the vane 30 is deflected to the left as a result. When the vane 30moves to the left, it carries with it the spool 20. The piston 22 slidesto the left, opening the input port 12 to the output port 14. At thesame time, the piston 23 moves to the left, better sealing the outputport 14 from the exhaust port 15. The movement of the spool 20 does notaffect any connection between the supply port 12 and the output port 13,but it does open output port 13 to the atmosphere to a greater extent.When the input pulse applied to the input 43 decays, the system returnsto its balanced condition with both the vane 30 and the spool 20 intheir intermediate central positions. The application of a subsequentpulse to the other signal input 44 produces the opposite actionconnecting the supply port 12 to the outputport 13.

If the supply port 12, which :is shown on the right side of the housing11, is connected to a similar chamber 128 on the left side of thehousing 11 by a small passage with limited fluid passing capacity, thenas the spool 20 is moved to the left, as discussed above,.and the port128 is opened to the output port 14, the fluid pressure in the port 128drops, decreasing the amount of fluid passing through the left opening51 and into the passage 27. This decreases the centering effect of thefluid being expelled from the perforation 31, and permits the furthermovement-of the vane 30 to the left. In fact,the system may be madeself-latching in this manner.

The above specification has describeda new and improved servo system inwhich a small pulse of fluid under pressure actuatesa valve to open alarger source of fluid under pressure for delivery to a utilizingdevice. The system of this invention operates in opposite directions topermit the control of two separate outputs by two separate inputs. It isrealized that the above description may indicate to others skilled inthe art additional ways in whichthis equipment .can be used withoutdeparting from its principles.

I claim:

1. A fluid servo valve comprising a valveblock and a control block, saidvalve blockcomprising ahousing'having a central chamber, a valve body'insaidchamber, a first inputport and a second input port communicatingwithsaid chambena first output port and a secondoutput,portcommunicating with said chamber, said valve having a firstvalve portion interposed between said first inputand output ports, saidvalve having a second valve portion interposed between said second inputand output ports, a vane connected to said valvebody, means within saidhousing for supplying fluid under pressure to both sides of said vane insubstantially equal quantities to maintain said vane and said valve bodyin a neutral position in which said first and second valve portionsprevent communication between said respective input and output ports,said control block comprising a primary input port for supplying fluidunder pressure to the interior of said control block, a first and asecond control output port, means within said control block for equallydividing fluid supplied to said primary input port between said firstand second control output ports, said first and second control outputport being arranged on either side of said vane, and means fordeflecting fluid supplied to said primary input port so that it is nolonger equally divided between said first and second control outputports to cause said vane to be deflected moving said valve bodyaccordingly to permit an input port to be connected to its respectiveoutput port.

2. The servo valve defined in claim I wherein said means in said controlblock for equally dividing fluid supplied thereto comprises a singleprimary conduit having as its input said primary input port, a pair ofsecondary conduits having as their respective outputs said first andsecond output ports, and a substantially sharp barrier interposedbetween said secondary conduits and at the center of the end of saidprimary conduit to divide the fluid stream in said primary conduit.

3. The servo valve defined in claim 2 wherein said deflecting meanscomprises a pair of tertiary conduits in said control block, one of saidtertiary'condui ts penetrating said control block to said primaryconduit immediately before and to one side of said sharp barrier, theother of said tertiary conduits penetrating said control block to saidprimary conduit immediately before and to the other side of said sharpbarrier so that a fluid injected into one of saidtertiarj conduits willcause the fluid passing through said primary conduit to pass unequallythrough said secondary conduits.

